Effect of Multiple Loading Rates on Uniaxial Compressive Strength of Rock

ABSTRACT: It is of crucial significance to study the effect of loading rate on the behaviour of rock because engineering structures are subjected to multiple loading conditions in their entire life. Although rock behaviour under single loading rate has been widely studied but very limited research has been conducted to study the performance of rock strength subjected to multiple loading conditions. This paper presents an experimental study of the effects of single and multiple strain rates on Sandstone samples. The first set of samples was tested at constant strain rates until failure to determine the peak uniaxial compressive strength (UCS). For the second set of samples, the first strain rate was applied to the sample up to a predetermined load, and then the second strain was initiated to find out the influence of multiple loading rates on the UCS of rock samples. 1. INTRODUCTION Geo-mining engineering deals with the extraction of minerals from the earth’s crust with the application of science and technology. Mining activities can cause severe disturbance in the natural environment, which results in the loss of hundreds of lives. For example, the misunderstanding of rock’s physical and mechanical properties in mining may lead to severe geological disasters which are to occur during the mining extraction process. Therefore, mining engineers must be concerned not only with the production and processing of minerals but also should anticipate the damage to be caused to the environment both during and after the extraction process in mining. Rock physical and mechanical properties are very important parameters for the safety and stability of any geo-mining engineering design and construction (Cheshomi et al, 2015; Khandelwal and Ranjith, 2017). There is an increasing trend towards infrastructural development all over the world. The extraction process of minerals from the earth’s crust may cause disturbance in the natural environment and may lead to geological disasters due to the misunderstanding of geo-mechanical properties (Du et al, 2020). Therefore, it is of great importance to investigate the effect of multiple loading rates on the uniaxial compressive strength of rock (Lajtai, 1991; Zhang et al, 1999, 2000; Khandelwal et al, 2013; Wang et al, 2020). These engineering structures are made either on the rock mass or in the rock mass. There is no denying the fact that engineering materials are subjected to multiple loading rates during their whole life (Li et al, 1998). The effects of single and multiple loading rates on strength with stress characteristics of rocks are important in defining input loading which is used in the mining designs. The effects of different strain rates have significant effects on the process of rock breakage as well as peak strength value (Olsson, 1991). Although material behaviour under a single loading mode has been extensively studied, very limited research has been conducted to investigate the performance of brittle materials subjected to varying loading conditions.